Such a mechanism is provided with a screw comprising an external thread, with a nut arranged around the screw and comprising an internal thread, and with a plurality of longitudinal rollers in engagement with the external and internal threads of the screw and the nut. Compared to a ball screw mechanism, a roller screw mechanism has the main advantage of providing higher approved load capacities.
A first type of roller screw mechanism comprises rollers exhibiting an external thread in engagement with the external and internal threads of the screw and the nut, and rolling in the nut around the screw in a constant axial position. Such a mechanism is known as a planetary roller screw.
A second type of mechanism comprises rollers without threads but provided with grooves, located in the interior of which are the external thread of the screw and the internal thread of the nut. During rotation of the screw or the nut, the rollers are displaced axially in the nut. After one complete revolution, each roller is returned to its initial position by means of cams fixed to the extremities of the nut. Such a mechanism is known as a recirculating roller screw.
With the current design of roller screw mechanisms, the zones of contact of the rollers on the flanks of the thread of the screw are generally decentred towards the vertex of the thread. In a similar manner, the zones of contact of the rollers on the flanks of the thread of the nut may also be decentred towards the vertex of the thread. This requires the load capacities of the roller screw mechanisms to be limited in order to avoid the appearance of stress concentrations at the level of the vertex of the thread of the screw and/or of the thread of the nut.
The present invention proposes to overcome these shortcomings